The Spread

Was the forecast right for Boston on Sun Aug 23?

Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the BOS observations

3 days out, 7 models put Boston's Sun Aug 23 high anywhere from 21° to 28°; by the final call the field had settled to a median of 23°. The day verified at 22° against the BOS observations, with 9.7 mm of precipitation — showers.

GEM landed closest, off by 0.7°. UKMO ran 5° hot.

3 days out the models said 21–28; it hit 22. GEM led (off 0.7°C); UKMO ran 5°C hot.
The shareable card for this receipt — what this page looks like pasted into a thread.

What every model said, at every lead

Daily-high calls for Sun Aug 23 as each model's runs approached it — the last archived run per day. NBM and The Spread's own blend are consensus products and stay out of these ranges and rankings; the Boston scoreboard shows them, labelled.

Lead AIFSAIGFSECMWFGEMGFSICONUKMO Range
3d · 2026-08-20 23° 23° 28° 25° 21° 24° 22° 21–28°
2d · 2026-08-21 23° 24° 27° 23° 21° 22° 25° 21–27°
1d · 2026-08-22 24° 24° 23° 26° 23° 22° 23° 22–26°
0d · 2026-08-23 23° 23° 23° 22° 23° 24° 27° 22–27°
actual 22°

Read it honestly

This is one date, not a league table. A model can win a day it deserved to lose; rankings only mean something over a window. For that, see which model has been most accurate in Boston — or every city The Spread scores.

Forecasts are what each model's archived runs said at the time, captured at The Spread's sweep times — never reconstructed after the fact. Truth is the BOS observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.